Developmental Aspects of TissueDevelopmental Aspects of Tissue Epithelial tissue
-germ layers: endoderm, mesoderm, ectoderm
Muscle and Connective tissue
-mesoderm
Nervous tissue
-ectoderm
Old age = decrease in mass & viabililty
Tissue RepairTissue Repair1. Regeneration
Replacement by the same kind of cells
2. Fibrosis Repair by dense fibrous
connective tissue (scar tissue)
3. Determination of method Type of tissue damaged
Severity of the injury
Events in Tissue RepairEvents in Tissue Repair1.Capillaries become very permeable
Clotting proteins leak through
Clot walls off injured area
2. Formation of granulation tissue
Many capillaries and WBCs
3. Regeneration of surface epithelium Develops beneath scab
Over the scar
Regeneration of TissuesRegeneration of Tissues Tissues that regenerate easily
- Epithelial tissue
- Fibrous connective tissue and bone
Tissues that regenerate poorly
- Skeletal muscle
Tissues that are replaced largely with scar tissue (amitotic at maturity)
- Cardiac muscle
- Nervous tissue within the brain and spinal cord
Changes in Growth PatternsChanges in Growth Patterns1.Neoplasm – mitosis gone crazy; tumor
• Benign – doesn’t spread; stays local
• Malignant – cancerous; invades; spreads via blood – called metastisis
• Carcinogens – agents that cause cancer; build up of mutations
2. Hyperplasia – temporary enlargement of localized tissues; i.e. breasts during pregnancy; can be normal or abnormal
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